1. Field of the Invention
The present invention relates to synthetic fibers for medical use and methods for making such synthetic fibers, and, more particularly, to synthetic fibers having cavities adapted to hold relatively large quantities of a medicament, for use in forming sutures, textile prostheses and medicated epidermal pads.
2. Description of the Related Art
Conventionally, synthetic fibers useful for medical applications such as sutures, textile prosthesis, and medicated pads that are applied to the skin, have been fabricated as solid fibers that carry a medicament. For example, U.S. Pat. No. 3,978,203 to Wise, incorporated herein by reference in its entirety, discloses medicine-bearing, polymer-based products, such as sutures and matrices formed in predetermined shapes for bodily implantation, which control the rate at which the medicine is released into the surrounding tissue.
U.S. Pat. No. 3,991,766 to Schmitt et al., incorporated herein by reference in its entirety, discloses absorbable surgical elements, such as sutures, clips, sponges, gauze, prosthetic devices, and storage pellets having medicaments incorporated therein which are released into tissue over time as the surgical element is absorbed. The medicament is combined with a base material of polyglycolic acid (PGA) and subsequently formed into the surgical elements, e.g., by being spun into filaments to form sutures.
Similarly, U.S. Pat. No. 5,010,167 to Ron et al., incorporated herein by reference in its entirety, discloses biocompatible, biodegradable polymers useful for making controlled release devices for drug delivery, such as bioabsorbable sutures, wherein the drug is incorporated directly into the polymer.
U.S. Pat. No. 4,024,871 to Stevenson, incorporated herein by reference in its entirety, discloses multifilament suture stands that are impregnated with an antimicrobial agent and top coated with a segmented polymer, such that the sutures retain antimicrobial properties over an extended period of time. The antimicrobial agent is distributed substantially throughout the suture in the interstices between strands and between individual filaments.
U.S. Pat. No. 5,378,540 to Olson, incorporated herein by reference in its entirety, discloses coating an absorbable braided suture with a solution that controls the release of chemical or pharmaceutical agents as the suture is absorbed into living tissue.
U.S. Pat. No. 4,841,968 to Dunn et al., incorporated herein by reference in its entirety, discloses biodegradable sutures having a core and sheath configuration, wherein the core comprises a blend of a polymer and an agent to be released into living tissue, and the sheath comprises only the polymer.
While these known synthetic fibers are effective in controlling the release rate of a medicament into tissue, these fibers are either solid fibers that require the medicine to be absorbed into the fiber or fibers comprising medicine intermixed with a polymer prior to extrusion and formation of the fibers from the mixture. Consequently, these fibers have a limited capacity to hold medicine. Accordingly, there remains a need for synthetic fibers useful for forming sutures, textile prostheses, medicated epidermal pads, and the like, that have the capacity to hold more medicine than conventional synthetic fibers.
It is an object of the present invention to provide synthetic fibers useful for forming sutures, textile prostheses and medicated epidermal pads, that are capable of holding a greater quantity of medicine than conventional synthetic fibers.
It is another object of the present invention to employ bicomponent fiber extrusion techniques to form synthetic fibers capable of storing medicine to be released into living tissue.
It is a yet another object of the present invention to provide for storage of medicine, to be time released into the body, in cavities formed in a synthetic fiber.
It is a further object of the present invention to employ single-component fiber extrusion techniques to form synthetic fibers capable of storing medicine to be released into living tissue.
The aforesaid objects are achieved individually and in combination, and it is not intended that the present invention be construed as requiring two or more of the objects to be combined unless expressly required by the claims attached hereto.
According to the present invention, a synthetic fiber is formed with a plurality of longitudinally-extending cavities which hold a medicament intended to be absorbed into living tissue brought into contact with the fiber. The fiber can be formed by dissolving a soluble polymer component of an extruded plural-component fiber, leaving cavities that extend inward from the outer surface of the fiber in the locations of the dissolved polymer. After the fiber has been exposed to a solvent, the cavities left by the dissolved component are filled with a medicament. Specifically, the cavities are filled with a medicament that is mixed with a viscous carrier which solidifies within the cavities. The fibers can be used to make sutures, textile prostheses for insertion into the body, and epidermal pads and bandages.
Fibers having internal cavities, i.e., cavities not extending to the external surface of the fiber, can be formed by extruding a single-component fiber from a spinneret orifice having a number of T-shaped slots extending from a central hub. A medicament is introduced into the internal cavities by soaking the fiber in a liquid containing the medicament. The internal-cavity fiber is therefore formed of polymer having some capability for liquid transport, e.g., nylon. A fiber with external cavities can be formed from a similar process by modifying one or more of the extrusion parameters.
Because the fiber of the present invention includes cavities or reservoirs specifically designed to hold a medicament, these fiber advantageously hold significantly more medicine that prior art fibers relying on absorption of a medicament by a fiber or formation of a polymer into which a medicament is intermixed.
The above and still further objects, features and advantages of the present invention will become apparent upon consideration of the following detailed description of specific embodiments thereof, particularly when taken in conjunction with the accompanying drawings wherein like reference numerals in the various figures are utilized to designate like components.